In the Ultimate comics Reed actually uses his stretchyness to make himself even more intelligent by creating new wrinkles and pathways in his brain with his powers. He fixes his astigmatism too by just stretching his eyes back in the right shape resulting in better than 20/20 vision. It's kind of weird comic book science but I think it's a cool evolution of stretchy powers, truly controlling and manipulating the plasticity of his body on a conscious level.